Published European patent documents EP-C-0 206 766 and EP-C-0 230 804 disclose metallic cylinder head gaskets for internal combustion engines, such gaskets comprising a carrier plate and at least one cover plate having resilient sealing projections, i.e., beads. The gap between the cylinder head and cylinder block of an internal combustion engine varies during operation as a function of the working cycle of the adjacent cylinder. A gasket disposed in the gap is subjected to constant changes in pressure and must have durable resilience properties in order to maintain a satisfactory seal.
In the gaskets of the above-identified publications, the head/block gap is sealed by means of an upward extension of the cylinder head gasket, which extends about the combustion space, in cooperation with a bead lying behind the extension. The bead, being resilient, follows vertical movements of the cylinder head in relation to the cylinder block in response to the ignition pressure. On the one hand, no unacceptably large deformation must occur when the bead is subjected to maximum compressive loading. On the other hand, the compressive force applied to the bead must not be completely released but, rather, must be maintained at least at a level which will ensure a minimum deformation with the maximum cylinder pressure. The working range of the bead thus lies between these two limits of deformation.
In order to ensure proper functioning, the bead must therefore not be completely deformed either during the installation of the gasket or in the operating state. An unacceptably large deformation of the bead vertically with respect to the plane of the gasket is prevented in known gaskets by means of a deformation limiter of constant thickness. The deformation limiter also serves to extend the gasket upwardly along the combustion space.
Prior art gaskets as exemplified by the above identified publications are not suitable for use on internal combustion engines having cylinder liners since the vertical forces which arise when the gasket is being clamped in position, or which exist after installation, are applied at the edge of the combustion space and thus essentially to the cylinder liner. These forces produce tilting moments on the liner. This occurs, in particular, if the distance between adjacent cylinder bores is small.
The object of the invention is to provide a cylinder head gasket which is suitable for internal combustion engines with cylinder liners.